Diagnostic errors are more frequently a result of the clinician's failure to combine medical knowledge adequately than of data inaccuracy. Diagnostic reasoning studies are valuable to understand and improve diagnostic reasoning. However, most diagnostic reasoning studies are characterized by some limitations which make these studies seem more simple than diagnostic reasoning in real life situations actually is. These limitations are connected both to the failure to acknowledge components of knowledge used in clinical practice as well as to acknowledge the physician-patient (...) relationship's influence on clinical knowledge and on the reasoning process itself. In addition the modes of reasoning described in these studies frequently is oversimplified. In this paper three simplistic and competing models of diagnostic reasoning are analyzed and criticized, followed by an evaluation of two alternative models proposing a combined view. (shrink)